Status:Closed    Asked:Jul 05, 2018 - 11:50 AM

Swap values and IPUMS-CPS ASEC extracts

1. Am I correct that the post-2010 IPUMS-CPS ASEC extracts contain swap values rather than raw top topcodes or average values?
2. Am I correct that the 1975-2010 swap values have not been inserted ointo the IPUMS-CPS extracts, but need to be separately replaced?

3. Based on discussions in the user forum, e.g. here:, and here: 76-2010-file-q2160102.aspx

it seems there was some ambiguity in the proper use of the rank proximity swap values for 1975-2010 values as of 2017. Have any of these questions been clarified to you in the interim? Do you continue to suggest the methodology suggested by lgautham? Are you now able to supply instructions on the correct ways to use the swap values to get consistant income accounting for IPUMS-CPS samples? Has there been any clarification at all since the questions noted above?

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Staff Answer


Jeff Bloem


I'll try to address each question one at a time.

(1) Yes, you are correct that the post-2010 IPUMS ASEC samples contain swap values, rather than topcodes.
(2) In the 1975 through 2010 samples, topcodes are used (rather than swap values) to preserve confidentiality of respondents. (See the table "All Income Components Topcodes by Year" on this page for more detail.)
(3) At the present time, we do not have any additional guidance on this topic. The IPUMS CPS team always aims to provide the best and most up-to-date documentation possible. At times this is complicated by missing or incomplete documentation in the source data files. In the case of the swap values, there does seem to be some ambiguity and if we uncover any additional details to share we will update the documentation available on the IPUMS CPS site as soon as possible.


Jul 09, 2018 - 09:27 AM

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